In a modern vehicle it is normally necessary to envisage the possibility of housing a spare wheel, which may be supplied as standard component or else as an optional component (in some markets the presence of the spare wheel is an indispensable requisite for enabling registration of the vehicle, whereas in other markets the presence of the spare wheel depends upon the will of the purchaser).
For automobile manufacturers, the presence of the spare wheel represents a constraint that requires consideration right from the design stage in so far as the spare wheel is an object of large dimensions (as compared to the dimensions of the compartments available for housing it) and high stiffness and typically must hence be appropriately positioned in order not to alter the response of the vehicle in the event of impact and hence not to alter the level of safety provided for the occupants of the vehicle.
For example, an automobile with a rear engine has a front boot compartment designed for housing the spare wheel. In order not to alter the response of the vehicle in the event of (front) impact, the spare wheel would have to be oriented in the front boot compartment in a vertical or quasi vertical position in order to minimize the longitudinal encumbrance and hence not to hinder controlled deformation of the front part of the vehicle during a front impact. In fact, if the spare wheel were set in the front boot compartment in a horizontal or quasi horizontal position, during a front impact the spare wheel itself would constitute a rigid body set longitudinally that opposes controlled deformation of the front part of the vehicle and hence that adversely affects the response of the automobile in the event of front impact. In other words, in the event of front impact the spare wheel set in the front boot compartment in a horizontal or quasi horizontal position tends to remain in the pre-impact position, getting jammed between the various elements of the car frame and hence reducing controlled deformation of the struts and thus increasing the level of deceleration experienced by the vehicle and by its occupants.
However, in a high-performance automobile with rear engine, the spaces available in the front boot compartment for housing the spare wheel are very limited since it is typically necessary to guarantee high aerodynamic performance (i.e., to maximize the penetration coefficient, at the same time reducing the area of the front section). In a high-performance automobile with rear engine, in order to maximize the aerodynamic performance, it would probably be necessary to set the spare wheel in the front boot compartment in the quasi horizontal position in so far as said quasi horizontal positioning enables a considerable reduction of the area of the front section (in addition to enabling also a certain reduction of the weight of the vehicle) as a result of a reduction of the transverse and vertical encumbrance.
U.S. patent application No. US2002185881A1, which is incorporated by reference, describes a vehicle comprising: a rear boot compartment; a spare wheel, which is housed within the rear boot compartment; and a thrust device, which is set within the rear boot compartment, comprises an inclined plane resting on which is a portion of the spare wheel, and pushes the spare wheel in an eccentric way in order to bring about a rotation of the spare wheel about a horizontal axis of rotation and towards a vertical position following upon a progressive reduction in the dimensions of the rear boot compartment during impact.